add parameter value checking

[samnemo]

Add parameter value checking from GUI, before the param files are written, to ensure that all parameters are within valid ranges. Otherwise, there can be problems when the simulation is run (e.g. numerical errors from NEURON, etc.).

[blakecaldwell]

@rythorpe @jasmainak there's been a lot of progress on this in hnn-core... great! Can you close this issue when appropriate and/or add a reference to the hnn-core issue in the next HNN release milestone https://github.com/jonescompneurolab/hnn/milestone/1

[jasmainak]

will do!

[blakecaldwell]

I realized there is more to closing this issue in HNN GUI. There needs to be feedback to the user when they input a parameter not accepted by hnn-core.